Radioactive materials are used in many fields, such as energy development, hydrocarbon exploration, medical and scientific research. In hydrocarbon exploration, specifically the drilling, evaluating, and production of oil & gas wells, the use of radioactive materials such as Cesium-137 or Americium-241 Berylium is common.
In an exemplary application, the radioactive source is located inside a carrier disposed within a downhole tool, such as a wireline logging, measurements-while-drilling (“MWD”), or logging-while-drilling (“LWD”) tool. The downhole tool is passed through a borehole penetrating a geological formation of interest. One conventional technique involves irradiating the formation with high-energy neutrons and monitoring the resulting energy spectra. The resulting energy spectra generally are indicative of characteristics of the formation. A radioactive source carrier is secured in a radiation shielded container when the radioactive source carrier is not inside the downhole tool.
A shielded container, referred to as a shield, is designed to absorb a significant portion of the ionizing radiation that is emitted from the radioactive source when the radioactive source is being stored, transported or otherwise not in use. Typically, a radioactive source spends the majority of its useful life stored in a shielded container. The radioactive source is removed occasionally either for its intended purpose or for routine inspections, physical inventories, calibrations, cleanings and other operations.
One or more shielded containers, containing radioactive sources, may be packaged within a larger container referred to as an overpack. An overpack is a container used for transporting cylinders not meeting shipping regulations, such as the regulations of the United States Department of Transportation. Therefore, the overpack is a container into which one or more cylinders would be placed for shipment. For example, one or more shielded containers may be packaged in the overpack while being transported from one location to another, such as from a base of operations to a job site. A metal overpack is designed, tested, and certified to meet all shipping requirements and would be suitable to contain, transport and store cylinder contents, regardless of cylinder condition.
Security and human health issues associated with radioactive materials lead to specific procedures that are intended to reduce human exposure to radiation, record radioactive source location, record radioactive source usage, perform physical radioactive source inventories, and ensure that sources are returned to the shielded container after each use. Much of these existing procedures presently rely on human involvement.
Additionally, numerous parties are involved in the handling of the radioactive source. The radioactive source, when not in use, is stored at a storage facility managed by a first party. When needed for energy exploration (or other purpose), the radioactive source is removed from storage and transported to the exploration site by a transportation party. In some cases, the exploration site is offshore. In such cases, the radioactive source is transported to a dock where a dock authority manages possession of the radioactive source. Thereafter, the radioactive source is transported by ship to the exploration site. Accordingly, multiple different parties handle the radioactive source, contained within the shield. Each party handling the radioactive source must manage, closely, multiple safety and reporting requirements associated with handling radioactive materials.
Therefore, there is a need in the art for an improved ability to inventory and track radioactive sources. In particular, there is a need for a device that is capable of remotely inventorying radioactive sources, tracking radioactive source locations and recording source usage.